1. Field of the Invention
This invention relates to a method on a truck for railway vehicles to measure the curvature of a track, and a method for configuring the steering orientation of an axle on a rail truck, which axle is rotationally fastened to a truck frame, as a function of the curvature of the track.
2. Description of the Prior Art
Most of the railway vehicles used in urban transit operations in particular have double-axle trucks. Multiple-axle trucks display poor cornering performance on the tight curves that are frequently required because of the layout of the streets. This phenomenon is observed primarily on railway vehicles, the wheels of which are rigidly connected to the truck frame in terms of their yawing movement.
One solution to this problem teaches that the axle or the wheels are mounted in the truck frame so that they can be steered. A steering movement that corresponds to the curvature of the track can be accomplished by a device that orients the axle or the wheels.
DE 195 38 379 C1 discloses a two-wheel truck with individual-wheel drive for vehicles that run on a guideway with controlled steering, in which the truck, for each axle, has two vertical swivel pins, one located on each side outboard of the wheel tread contact points, wherebyxe2x80x94by blocking the position of the swivel pin that is currently on the outside of the curvexe2x80x94the axle is rotated alternately precisely around this blocked swivel pin.
DE 92 19 042 U1 discloses a method for the detection of curves that measures the curvature of the track by means of inductive sensors.
The prior art also includes methods in which the wheels or axles are steered passively. This steering can be accomplished either by the tracking forces or by a mechanical coupling of the axle position with the angle of rotation between the car bodies. One disadvantage of these mechanical solutions, however, is that they make possible only a very approximate and imprecise steering.
A precise orientation is possible only if the axle is actively controlled, e.g. by means of a servo-drive. The regulation of the steering angle which corresponds to the relative angle between the wheel or axle and the truck frame requires the specification of a steering angle setpoint. In turn, the determination of the steering angle setpoint requires a knowledge of the curvature of the track.
The object of the invention is to create a method to measure the curvature of the track for railway vehicles, so that this value can be used to calculate the setpoint for the regulation of the steering angle.
The invention teaches that this object can be accomplished by calculating the curvature of the track is calculated by dividing a yaw rate by a translation rate, and the wheels are oriented on the basis of a setpoint steering angle that is calculated by multiplying the curvature of the track by one-half the distance between the two axles of the truck.